Manufacture and production of artificial silk



Patented May 22, 1928.;

.UNSITED sra'rssf PATENT OFFICE.

caoan'sm maanmrn w'nrr'raxsa, or cnminm nouns, anamnn, assreuoa 'ro cons-norms 1.1mm, or Lonnon, sacrum.

nanurac'ruaa AND raonvcrron or aarm rcmn smz No Drawing. Appiication filed June 1, 1926, Serial No. 118,197, and in Great Britain July 87, 1885.

When dyeing a number of skeins of artificial silk in the same dyebath, and under the sameconditions, it is frequently found that some skeins have absorbed more dye than 8 others, with the result that the skeins are not all of the same shade. This difference in aflinity varies according to the dyestuif employed. Wilson & Imison, Journal Soc.

Chem. Ind. 1920, p. 323T have pointed out .1 that dyestuffs of high molecular weight tend to produce more uneven shades, while dyestuffs of lowmolecular weight give more even shades. The difference in affinity for the dye appears to arise from diflferencesjn the said silk, which differences are disadvantageous, because when, before being dyed 3 several skeins having such differences between them, are used in making a fabric, this fabric, on being subjected to subsequent dye- .in'g operations, may not be and some parts appear darker. than other parts, and such fabrics may consequently be unsaleable, or much depreciated in value.

There has not hitherto, so far as I am aware, been anyway in which the character of artificial silk in this respect can be ascertained before fabrics are made therefrom and this is very disadvantageous as suchsilk, in its undyed condition, is a' manufactured article put upon the market and sold to manufacturers to make up into fabrics and afterwards dye.

This invention has for "its object to overcome this difiiculty and to provide quantities of undyed viscose artificial silk the whole of which can be relied upon to have practically equal dyeing effect by taking a quantity of viscose artificial silk in portions which I will refer to dyeing process for the same: length of time With the same bath, using a dyeing agent whichtends to produce uneven shades and which is also easily modified so as to become colorless, and afterwards sorting these skeins into batches each consisting of those which have become coloured to the same, or practically the same shade. The dyeing matter is then modified so as to become colorless in the several batches so that separate batches of undyed artificial silk, of practically cqual dyeing aflinity throughout, are obtained, and, if these batches be afterwards put upon the market and employed separately for the production of fabric, such fabric can be dyed dyed uniformly aflinity'. This I as skeins and subjecting all these skeins to a batches of viscose artificial silk which are with the practical certaintv (if the dyeing be properly. carried out) of obtaining the same shade throughout the fabric, or those parts of a fabric in the making of which the same batch has been used.

Should any single skein itself be composed of two or more parts which become unevenly coloured, such skein would also be removed from the other skeins.

In carrying .out the preliminary dyeing 06 according to this invention, use should be madejof a dyestufi which can readily be modified so as to become colorless, for example, by bleaching with a dilute solution of sodium hypochlorite, or of calcium h pochlorite, or of hypochlorous acid of so ium hydrosulphite, or any other suitable reducing or oxidizing agent. A list of dyestuffs which tend to give uneven shades on artificial silk is given by Wilson and Imison, and the majority of the dyestuffs mentioned there can be bleached by means of sodium hypochlorite. The following may be mentioned however as particularly suitable for use according to this invention Color g M index No. Chlorazol'fast pink BK 353 Chlorazol sky blue FF 51 Direct blue 2B Q 40 Direct green G 594 perature, since, as pointed out by Wilson and Imisonfa lower temperature tends to enhance the unevenness of the dyein In the term artificial silk include silk whether in the finished state, or in an suitable stage of its production.

What I claim is 1. The processforproducing batches of viscose artificial silk, the whole of each of which 'will. have practically the same dyeing aflinity so that fabrics made therefrom can be dyed to the same shade, the said process consisting in subjecting a quantity of viscose artificial silk in portions, or skeins,'to the same dyeing operation using a dyeing agent which is liable to produce uneven shades on not uniform with each other, which dyeing agent can also easily be modified so as to become colorless, and afterwards. sorting these portions, or skeins, into batches each consisting of those which have become dyed, 110

or colored, to the same, or practically the same, shade and afterwards modifying the said dyeing agent so as to render it colorless and thereby producing 'se'parate batches of 5 undyed artificial silk, ea-clr'batch of practically-equal dyeing afiinity throughout.

2. The process of" producing batches of viscose artificial silk, the whole of each of which will have practically the same dyeing Ill aflinity so that fabrics made therefrom can be dyed to the same shade, the said process consisting in subjecting aquantity of viscose artificial silk in portions, or skeins, to the.

same (1 eing operationusing chlorazol fast pink B and afterwards sortin these portions, or skeins into batches'eacfi consistin of those which have become dyed, or colore to the same, or practically the same, shade and afterwards modifying the chlorazol fast ink BK. so as to render it colorless, and t ereby producing separate batches of 'undyed artificial silk, each batch of practically equal dyeing aflinity throu hout.

In testimony whereof fhave signed my name to this specification.

CROYDEN MEREDITH WHITTAKER. 

